I have tried the same setup (but with a different plugin, OB-XD, controlling the detune and xmod with CC17). It works, at least on my system. I am on Cantabile 4196.
Which version of Cantabile are you using? The binding system has been changed at some point (after 4100).
Gabriel
P.S: you could also try adding a delay to the second binding, in case the plugin needs some time the process the first one.